ch 2 single-gene inheritance Flashcards

1
Q

chromatin

A

the substance of chromosomes
- now known to include DNA and chromosomal proteins

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2
Q

histone

A

a type of basic protein that forms the unit around which DNA is coiled in the nucleosomes of eukaryotic chromosomes
- H1 histone - make sure the nucleosomes get lined up correctly

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3
Q

nucleosome

A

the basic unit of eukaryotic chromosome structure; a ball of eight histone molecules that is wrapped by two coils of DNA
- associate with and coil around H1 histone

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4
Q

telomere

A

chromosome end

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5
Q

centromere

A

area of constriction

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6
Q

nucleolar organizer

A

tandem repeats of rRNA genes

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7
Q

heterochromatin

A

dense chromatin
- will appear darker with stain, more constricted

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8
Q

euchromatin

A

less dense chromatin

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9
Q

true-breeding

A

genotype is homozygous

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10
Q

dominant phenotype

A

the parental phenotype that is expressed in a heterozygote

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11
Q

dominant allele

A

an allele that expresses its phenotypic effect even when heterozygous with a recessive allele
- is A is dominant over a, then A/A and A/a have the same phenotype

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12
Q

recessive phenotype

A

the parental phenotype that is not expressed in the heterozygote

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13
Q

recessive allele

A

an allele whose phenotypic effect is not expressed in a heterozygote

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14
Q

first filial generation (f1)

A

the first generation resulting from a controlled cross between two known parents

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15
Q

second filial generation (F2)

A

the second generation resulting from a controlled cross between two known parents, generated by selfing/intercrossing the F1 generation

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16
Q

product rule

A

the probability of two independent events occurring simultaneously is the product of their individual probabilities

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17
Q

sum rule

A

the probability that one or the other of two mutually exclusive events will occur is the sum of the individual probabilities

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18
Q

Mendel’s law of equal segregation

A

two members of a gene pair segregate equally into the gametes, so that half the gametes carry one allele and the other half of gametes carry the other allele
-each parent contributes 1 copy of each factor to offspring with equal frequency
- gametes are haploid, fuse to form diploid offspring

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19
Q

test cross

A

a cross of an individual organism of unknown genotype or a heterozygote with a tester

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20
Q

tester

A

an individual organism homozygous for one or more recessive alleles

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21
Q

Mendel’s overall conclusions (5)

A
  1. difference btw yellow and green traits is that they carry a discrete and different hereditary determinant (mendel’s particulate factors)
  2. factors exist in pairs
  3. in each pair, one of the factors is dominant to the other (recessive and dominant alleles)
  4. parents pass one copy of each factor onto offspring; diploids produce haploid gametes, that have one cope of each gene, or one member of each homologous pair
  5. factors from parents unite independently of the type of factor; gametes fuse randomly
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22
Q

chromatid

A

one of the two side by side replicas produced by chromosome replication

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23
Q

sister chromatids

A

the juxtaposed pair of chromatids arising from the replication of a chromosome

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24
Q

homologous chromosomes

A

chromosomes that pair with each other during meiosis and (usually) have the same genetic loci (may have different alleles)

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25
Q

dyad

A

a pair of sister chromatids joined at the centromere

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26
Q

tetrad

A

four homologous chromatids in a bundle in the first meiotic prophase and metaphase

27
Q

chiasma

A

a cross-shaped structure commonly observed btw non sister chromatids in meiosis
- the site of crossing over

28
Q

s-phase

A

DNA molecules replicate to form identical chromatids
- making a copy of the existing DNA

29
Q

molecular marker

A

a site of DNA heterozygosity (difference), not necessarily associated with phenotypic variation, used as a tag for a particular chromosomal locus

30
Q

hemizygous gene

A

a gene that is present in only one copy in a diploid organism

31
Q

reciprocal crosses

A

a pair of crosses of the type genotype A (female) x genotype B (male) and B (female) x A (male)

32
Q

prophase

A
  • chromatids coil and condense to become visible
  • mitotic spindle forms outside of nucleus, consists of microtubules
  • nuclear envelope breaks down and nucleoli disappear
  • kinetochores form on each face of the centromere
33
Q

kinetochore

A

multiprotein complex that binds to centromere
- site of attachment for microtubules

34
Q

metaphase

A
  • chromosomes align along the metaphase plate
35
Q

anaphase

A
  • centromeres and sister chromatids separate from chromosomes
36
Q

telophase

A
  • migration of chromosomes to the poles is complete
  • nuclear envelope reforms
37
Q

cytokinesis

A

cellular division takes place to form the 2 new daughter cells (genetically identical)

38
Q

mitosis generates

A

cells identical to mother cell

39
Q

interphase

A

G1, S, G2

40
Q

M phase

A
  1. prophase
  2. metaphase
  3. anaphase
  4. telophase
41
Q

meiosis generates

A

haploid cells from diploid

42
Q

MI

A

align and separate homologous pairs
- reduced division

43
Q

MII

A

separate sister chromatids
- equational division

44
Q

prophase 1 (5 phases)

A

leptotene, zygotene, pachytene, diplotene, diakinesis

45
Q

leptotene

A

chromosomes condense
- become visible

46
Q

zygotene

A

pairing of homologues, crossing over
- synaptonemal complex begins to form

47
Q

pachytene

A

synaptonemal complex complete (compressed)

48
Q

diplotene

A

slight separation of synaptonemal complex to form chiasmata

49
Q

diakinesis

A

further contraction of synaptonemal complex (compressed again)

50
Q

synaptonemal complex is made of

A

DNA and protein

51
Q

function of the synaptonemal complex

A

facilitates crossing over

52
Q

metaphase 1

A
  • homologs move to the equatorial plane
  • centromeres attach to the spindle
  • line up as tetrads
53
Q

anaphase 1

A
  • one homolog moves to each pole
  • sister chromatids DO NOT separate
  • separate homologous pairs (still dyads)
54
Q

telophase 1

A
  • migration complete
  • nuclear membrane MAY reform
  • cytokinesis MAY occur
55
Q

prophase 2

A

condensed chromosomes

56
Q

metaphase 2

A

dyads aligned along equatorial plane

57
Q

anaphase 2

A

separation of centromeres and sister chromatids
- results in two chromosomes

58
Q

telophase 2

A

nuclei reform
cytokinesis to produce 4 haploid daughter cells

59
Q

sex-linked single-gene inheritance patterns

A

genes that show different phenotypic ratios

60
Q

autosomal dominant pedigree

A
  1. trait appears in every generation
  2. affected parents have affected children
  3. no correlation between sex and a particular phenotype
61
Q

x-linked recessive pedigree

A
  1. phenotype is more common in males than females
  2. affected fathers have no affected children - however, all daughters are carriers
  3. trait passed from grandfather to grandson
62
Q

x-linked dominant pedigree

A
  1. fathers pass traits to all daughters - however, no sons are affected
    2, mothers pass trait to half sons and daughters
63
Q

y-linkage

A

no conclusive cases
1. phenotype passed from father to all sons - not to daughters